Newbie question about SQL -243 ISAM -154 Lock Timeout Expired

I begin work, declare a cursor which carries out a select for update on a given table, then I open the cursor and repeatedly carry out fetches, but no updates! There is a second thread in the same process which carries out a short single executed select on the same table about once every minute, but also there is a second process which carries out a similar iteration of the table using an open cursor (though not for update) and fetches, but this has a much narrower selection criteria and should in theory not take long One of the fetches in the first process fails SQLCODE -243, ISAM -154 Lock Timeout Expired, when the fetch fails I execute rollback work. 1. Will the rollback ensure that the cursor/locking is closed and freed ? 2. LOCK MODE WAIT is set to 5, I would have thought this was sufficient. Do the circumstances suggest I may have some locking feature incorrectly set. 3. I don't fully understand what the isam -154 error text means when it says the server is waiting for another server. Is there one informix server process per cient process, or per connection (possiblky per thread) or what? Hoping some-one can advise, more info available if necessary. Andrew H. sending to informix-list